China has officially released the implementation guidelines for the recommended national standard GB/T 46991.1-2025, which governs how battery health information is measured and displayed in light-duty passenger electric vehicles. The announcement, covered by CCTV News on August 2, outlines specific limits on the discrepancy between what a vehicle's dashboard shows and the actual measured battery state, alongside durability reference levels tied to vehicle age and accumulated mileage.
The standard was developed under the supervision of the Ministry of Industry and Information Technology (MIIT) and the Standardisation Administration of China (SAC), with a drafting expert group led by Yu Yang. It is a recommended national standard, not a mandatory safety regulation, and applies exclusively to light-duty passenger EVs.
Display Accuracy: 5% Error Cap
A central element of the standard is the accuracy of battery health information presented to drivers. It introduces the concept of State of Available Energy (SOCE), defined as the ratio of a battery's current available energy to that of a brand-new battery. Unlike State of Charge (SOC), which reflects remaining energy during operation, SOCE is designed to indicate long-term capacity retention.
Under the new rules, the relative deviation between the displayed SOCE value and the physically measured value must not exceed 5%. This means the displayed number cannot differ from the actual measured result by more than 5%, providing a clear benchmark for comparing dashboard readings with real battery capacity.
Virtual Mileage for Non-Driving Energy Use
The standard also tackles energy consumption that occurs outside of driving. Non-driving discharge, such as power used by vehicle systems when parked or while operating accessories, must be converted into an equivalent Virtual Mileage. This figure is calculated by converting non-driving energy consumption into a distance based on the vehicle's energy consumption rate. The displayed Virtual Mileage must remain within a 3% relative deviation from the measured value. The publicly available summary does not specify detailed testing conditions for different accessory loads or stationary power usage scenarios.
Durability Benchmarks
GB/T 46991.1-2025 establishes minimum SOCE retention levels for light-duty passenger EVs, based on vehicle age and accumulated mileage:
- 5 years, 100,000 km: SOCE ≥ 82%
- 8 years, 160,000 km: SOCE ≥ 75%
- 10 years, 200,000 km: SOCE ≥ 70%
These figures represent the remaining available energy compared with the vehicle's original factory-available energy. For instance, a battery with an initial capacity of 100 kWh would need to retain at least 82 kWh after five years or 100,000 km. The guidelines apply only to light-duty passenger vehicles, and it remains unclear if similar thresholds will be extended to commercial vehicles, buses, trucks, or two-wheelers.
Regulatory Context and Implications
This disclosure is part of China's broader efforts to develop standards for EV battery quality, recycling, safety, and lifecycle management. GB/T 46991.1-2025 focuses on battery health measurement, display accuracy, and durability evaluation, and is separate from mandatory safety standards like GB 38031-2025, which includes requirements on thermal runaway. As a recommended standard, it does not carry administrative penalties, mandatory recalls, or enforcement actions for vehicles exceeding the specified deviation limits.
Battery condition has become a critical factor in warranty discussions, used vehicle valuations, and long-term ownership decisions. Growing concerns about how charging habits—especially frequent fast charging—affect battery ageing have also heightened the need for accurate battery condition assessment. Discrepancies between displayed battery information and actual condition have underscored the importance of consistent measurement and evaluation methods.
Impact on the Used EV Market
Battery health is a key consideration in used EV evaluations, warranty negotiations, and lifecycle assessments. By defining measurement methods for SOCE accuracy, Virtual Mileage calculation, and durability benchmarks, GB/T 46991.1-2025 offers a common reference for assessing battery condition. The real-world impact on used EV pricing, warranty disputes, and consumer evaluation practices will depend on how automakers, testing organizations, and the broader market adopt and apply these requirements over time.
